Touch Screen Panel (TSP) in Cell technique is to manufacture a TSP sensor and a driving circuit thereof on an array substrate by an array process. The TSP sensor is integrated with a liquid crystal cell of the panel of the Liquid Crystal Display (LCD) so that the product is light and thin and has versatile functionalities. Therefore, the reliability of the touch panel is effectively improved.
FIG. 1(a) and FIG. 1(b) show a basic light induced TSP in Cell circuit in the prior art. As shown in FIG. 1(a), the sensor senses light using a photodiode D1 and generates electric leakage to detect a touch signal. As shown in FIG. 1(b), the sensor senses light using a sensitive capacitor C2 and detects the touch signal by the coupling of the sensitive capacitor and the change of the capacitor. Thin-Film Transistor (TFT) T1 functions as an amplifying transistor to amplify the voltage change across D1 after detecting the touch signal, increase the driving capability of the TSP in Cell circuit output, so that an external readout circuit for TSP may correctly read out the detection result.
Active Matrix Organic Light Emitting Diode (AMOLED) has a faster response speed, a higher contrast ratio and a wider angle of view as compared with a traditional liquid crystal panel. AMOLED Pixels are driven to emit light by a relevant driving circuit on the array substrate. FIG. 2 shows an AMOLED pixel unit circuit according to an embodiment.
If the TSP in Cell circuit as shown in FIG. 1(a) or FIG. 1(b) is simply integrated into the AMOLED pixel unit circuit as shown in FIG. 2, except for the existing five TFTs and two capacitors, three TFTs and one capacitor are required to be added, and respect to the control signals, except for the existing three control signals and two power sources, three control signals are required to be added. However, there is not enough space in the AMOLED pixels for the addition of these TFTs and signal lines. Therefore, in the prior art, the TSP in Cell circuit cannot be integrated into the AMOLED pixel unit circuit.